Communications networks are commonly used to enable end devices such as computers, servers, memory devices and the like to communicate with each other and/or to communicate with remote devices via one or more external telecommunications links. These networks include, among other things, communications cabling and connectors (also referred to herein as “connector ports”) that are used to interconnect the end devices, as well as network switches and routers that are used to route communications between the end devices. The end devices typically include a connector port such as, for example, an RJ-45 jack. The end device may be connected to the network by plugging a “patch cord” (i.e., a communications cable that has a connector such as an RJ-45 plug terminated on at least one end thereof) into this connector port, and then connecting the far end of the patch cord, either directly, or via additional communications cables, connectors and/or routers, to a connector port on a network switch. The network switch routes data signals that are transmitted from the end device toward their intended destinations (e.g., to other end devices, an external network, etc.), and likewise routes incoming data signals to the end device, as appropriate.
In many networks, each communications cable in the network includes eight insulated conductors such as copper wires that are arranged as four pairs of conductors, where the two conductors of each pair are tightly twisted together. Such cables are commonly referred to as “Ethernet” cables. Differential signaling techniques may be used to transmit a single information signal over each pair of conductors (referred to herein as a “differential pair” or simply as a “pair”) in an Ethernet cable. With differential signalling, the signals transmitted on each conductor of the differential pair have equal magnitudes, but opposite phases, and the information signal is embedded as the voltage difference between the signals carried on the two conductors of the pair.
In many applications, it may be important that both the length and duration of any failures in the communications network be minimized. For example, commercial data centers are now commonly used by online retailers, Internet portals, search engine companies and the like to provide large numbers of users simultaneous, secure, high-speed, fail-safe access to their web sites and/or to run the computer-based applications that handle the core electronic business and operational data of those organizations. These data centers may host hundreds, thousands or even tens of thousands of servers, memory storage systems and other associated equipment that are interconnected via a communications network. Prolonged or even short failures in these communications networks can have drastic consequences for an organization in terms of lost sales, decreased productivity and the like.